Three kinds of bimetallic Schiff base titanium complexes with different substituent moieties on organic ligands were synthesized.Ring-opening polymerizations (ROP) of lactides were carried out by using these titaniu...Three kinds of bimetallic Schiff base titanium complexes with different substituent moieties on organic ligands were synthesized.Ring-opening polymerizations (ROP) of lactides were carried out by using these titanium complexes as catalysts.The polymerization data and kinetic studies showed that complex 1a had the highest activity and complex 2a had the lowest activity for ROP of lactides.Moreover,all these three newly synthesized bimetallic titanium complexes showed higher polymerization activity and better molecular weight control than their monometallic counterparts reported in our previous work.展开更多
The aim of this study was to investigate the inhibitory effect of heparin/fibronectin (Hep/Fn) complexes on neointimal hyperplasia following endovascular intervention. Hep/Fn complexes were immobilized onto titanium...The aim of this study was to investigate the inhibitory effect of heparin/fibronectin (Hep/Fn) complexes on neointimal hyperplasia following endovascular intervention. Hep/Fn complexes were immobilized onto titanium (Ti) surfaces, with subsequent X-ray photoelectron spectroscopy (XPS), Toluidine Blue 0 (TBO) and immunohistochemistry methods were used to characterize surface properties. Smooth muscle cell (SMC) cultures were used to evaluate the effect of Hep/Fn complexes on SMC proliferation. Results showed that Hep/Fn complexes successfully immobilized onto Ti surfaces and resulted in an inhibition of SMC proliferation. This study suggests that Hep/Fn surface-immobilized biomaterials develop as a new generation of biomaterials to prevent neointimal hyperplasia, particularly for use in cardiovascular implants.展开更多
A monocyclopentadienyl titanium complex containing 8-quinolinolato (QCpTiCl_2) was synthesized. Its activities in ethylene polymerization at various Al/Ti molar ratios, different temperatures and activation time were ...A monocyclopentadienyl titanium complex containing 8-quinolinolato (QCpTiCl_2) was synthesized. Its activities in ethylene polymerization at various Al/Ti molar ratios, different temperatures and activation time were investigated. The activity with a Al/Ti molar ratio of 500 exhibited a maximum of 2.8×10~5 g/(mol.h) at 30℃. The activation time of QCpTiCl_2 with MAO before polymerization also plays a role on the activity. The structural properties of the produced polyethylene (molecular weight, molecular weight distribution and melting point) were discussed. Kinetic behaviors of ethylene polymerization with the QCpTiCl_2/MAO system at different Al/Ti molar ratios were studied. For the QCpTiMeCl/MAO system and the CpTiMe_2Cl/MAO system, binding energies of the examined intermediates were calculated by quantum-mechanical method based on ADF program, respectively. It is confirmed that the chlorinebridged adduct formed by the reaction of QCpTiMeCl with MAO is thermodynamically steady. In the case of the QCpTiMeCl/MAO system, olefin-separated ion pair (OSIP) mechanism is much favorable than ion-pair dissociation (IPD) mechanism. The experimental result on the CpTiMe_2Cl/MAO system showed lower activity for ethylene polymerization than that on the QCpTiMeCl/MAO system, which revealed that the CpTiMe_2Cl/MAO system is unfavorable to form active species with ethylene.展开更多
The condensation of acetylacetone (CH3COCH2COCH3) with benzdine (H2N-C6H4-C6H4-NH2) yielded diimine ligand 1 [HOC(Me)C(H)(Me)C=N(p-C6H4)(C6H4-p)N= C(Me)C(H)C(Me)OH)], which was converted into sodi...The condensation of acetylacetone (CH3COCH2COCH3) with benzdine (H2N-C6H4-C6H4-NH2) yielded diimine ligand 1 [HOC(Me)C(H)(Me)C=N(p-C6H4)(C6H4-p)N= C(Me)C(H)C(Me)OH)], which was converted into sodium salts. And then the sodium salts reacted with monosalicylaldiminato titanium complex 2{[3,5-di-But′2-(O)C6H2CHN(PH)]TiCl3(THF)} in dried dichloromethane to give a new benzdine-bridged binuclear complex 3{[3,5-di-Bu′-2-(O)C6H2CHN(PH)]2 [OC(Me)C(H)(Me)C=N(p-C6H4)-(C6H4-p)N=C(Me)C(H) C(Me)]Ti2Cl4}. The complex 3 was characterized by ^1HNMR and elemental analysis. In the presence of MAO(methylaluminoxane), the complex 3 in toluene was effective to catalyze polymerization, affording moderately high catalytic activity 1.93 × 10^5 g PE/(mol.Ti.h)]and high molecular weight polyethylene [5.63× 10^5 g/moll. The high temperature gel permeation chromatography (GPC) curve of polyethylene obtained revealed a single peak, but the molecular weight distribution (MWD = 3.21) is obviously broader than that of the similar mononuclear titanium complex. The melting points of the obtained polyethylene reaches 138 ℃, indicating that the polyethylene is of high crystallinity.展开更多
-The i. r. spectra of Na4 [UO2 (CO3)3], Na [UO2 (OH)3] and the surface species of uranium on HTO underthe condition of flowing natural seawater and concentrated seawater (NaCl-NaHCO3-U) were recorded, with the bands o...-The i. r. spectra of Na4 [UO2 (CO3)3], Na [UO2 (OH)3] and the surface species of uranium on HTO underthe condition of flowing natural seawater and concentrated seawater (NaCl-NaHCO3-U) were recorded, with the bands of urany! of surface species obtained and the finding that iigands of surface species besides HTO are mainly water and OH, and there are some CO32- groups under the condition of natural seawater. Some relations between the complex properties and the j. r. spectroscopic characters for uranyl complexes were studied, and the transferred change quantity of surface complex was calculated.Structure models for surface species of adsorption are herein presented and the mechanism for uranium adsorption is deduced.展开更多
Two ligand bridged binuclear titanium complexes Ti2(bppda)3(NMe2)2·3THF (1) and Ti2(bppda)3(NEt2)2·3THF (2) and one bis-ligand coordinated mononuclear complex Ti(bppda)2 (3) (ligand- HEbppda...Two ligand bridged binuclear titanium complexes Ti2(bppda)3(NMe2)2·3THF (1) and Ti2(bppda)3(NEt2)2·3THF (2) and one bis-ligand coordinated mononuclear complex Ti(bppda)2 (3) (ligand- HEbppda=N,N'-Bis(2-pyrrylmeth- ylidene)-1,2-phenylenediamine) were synthesized by adjusting the ratio of the starting materials and the reaction speed. The complexes were fully characterized with NMR, elemental analysis and X-ray crystal diffraction. The catalytic activity of the complex 1 to phenylacetylene hydroanilination reaction was also investigated.展开更多
The trichlorozirconium η~2-hydrazonides(R=H, A; R=CH_3, B) were synthesized through the finely controlled stoichiometrical reactions of anhydrous zirconium tetrachloride with the lithium salt of either 1-(furan-2-...The trichlorozirconium η~2-hydrazonides(R=H, A; R=CH_3, B) were synthesized through the finely controlled stoichiometrical reactions of anhydrous zirconium tetrachloride with the lithium salt of either 1-(furan-2-ylmethylene)-2-phenylhydrazonide or 1-(furan-2-ylethylidene)-2-phenyl hydrazonide in the solvent tetrahydrofuran(THF), respectively. These complexes were highly sensitive to air and moisture due to solely using less bulky ligand of hydrazonides. The molecular structures of the title complexes, determined by means of single crystal X-ray diffraction, were found to be the distorted pentagonal bipyramid geometry around zirconium atom, with three chlorides and the hydrazonato ligand acting as the η~2-coordination mode as well as two incorporated THF molecules. Upon activation with either methylaluminoxane(MAO) or modified methylaluminoxane(MMAO), both complexes A and B exhibited catalytic activities toward ethylene polymerization, producing polyethylenes with ultra-high molecular weights.展开更多
文摘Three kinds of bimetallic Schiff base titanium complexes with different substituent moieties on organic ligands were synthesized.Ring-opening polymerizations (ROP) of lactides were carried out by using these titanium complexes as catalysts.The polymerization data and kinetic studies showed that complex 1a had the highest activity and complex 2a had the lowest activity for ROP of lactides.Moreover,all these three newly synthesized bimetallic titanium complexes showed higher polymerization activity and better molecular weight control than their monometallic counterparts reported in our previous work.
基金supported by the financial support of Natural Science Research Program of Jiangsu Education Department(No.13KJB310014)Natural Science Foundation of Jiangsu Province(BK20140429)the Natural Science Foundation of Nantong University(No.14ZY015,No.13R23)
文摘The aim of this study was to investigate the inhibitory effect of heparin/fibronectin (Hep/Fn) complexes on neointimal hyperplasia following endovascular intervention. Hep/Fn complexes were immobilized onto titanium (Ti) surfaces, with subsequent X-ray photoelectron spectroscopy (XPS), Toluidine Blue 0 (TBO) and immunohistochemistry methods were used to characterize surface properties. Smooth muscle cell (SMC) cultures were used to evaluate the effect of Hep/Fn complexes on SMC proliferation. Results showed that Hep/Fn complexes successfully immobilized onto Ti surfaces and resulted in an inhibition of SMC proliferation. This study suggests that Hep/Fn surface-immobilized biomaterials develop as a new generation of biomaterials to prevent neointimal hyperplasia, particularly for use in cardiovascular implants.
基金The work is sub sidized by Special Funds for Major State Basis Research Projects of China(No.G1999064801)
文摘A monocyclopentadienyl titanium complex containing 8-quinolinolato (QCpTiCl_2) was synthesized. Its activities in ethylene polymerization at various Al/Ti molar ratios, different temperatures and activation time were investigated. The activity with a Al/Ti molar ratio of 500 exhibited a maximum of 2.8×10~5 g/(mol.h) at 30℃. The activation time of QCpTiCl_2 with MAO before polymerization also plays a role on the activity. The structural properties of the produced polyethylene (molecular weight, molecular weight distribution and melting point) were discussed. Kinetic behaviors of ethylene polymerization with the QCpTiCl_2/MAO system at different Al/Ti molar ratios were studied. For the QCpTiMeCl/MAO system and the CpTiMe_2Cl/MAO system, binding energies of the examined intermediates were calculated by quantum-mechanical method based on ADF program, respectively. It is confirmed that the chlorinebridged adduct formed by the reaction of QCpTiMeCl with MAO is thermodynamically steady. In the case of the QCpTiMeCl/MAO system, olefin-separated ion pair (OSIP) mechanism is much favorable than ion-pair dissociation (IPD) mechanism. The experimental result on the CpTiMe_2Cl/MAO system showed lower activity for ethylene polymerization than that on the QCpTiMeCl/MAO system, which revealed that the CpTiMe_2Cl/MAO system is unfavorable to form active species with ethylene.
基金Fund by the National Natural Science Foundation of China (20374043)
文摘The condensation of acetylacetone (CH3COCH2COCH3) with benzdine (H2N-C6H4-C6H4-NH2) yielded diimine ligand 1 [HOC(Me)C(H)(Me)C=N(p-C6H4)(C6H4-p)N= C(Me)C(H)C(Me)OH)], which was converted into sodium salts. And then the sodium salts reacted with monosalicylaldiminato titanium complex 2{[3,5-di-But′2-(O)C6H2CHN(PH)]TiCl3(THF)} in dried dichloromethane to give a new benzdine-bridged binuclear complex 3{[3,5-di-Bu′-2-(O)C6H2CHN(PH)]2 [OC(Me)C(H)(Me)C=N(p-C6H4)-(C6H4-p)N=C(Me)C(H) C(Me)]Ti2Cl4}. The complex 3 was characterized by ^1HNMR and elemental analysis. In the presence of MAO(methylaluminoxane), the complex 3 in toluene was effective to catalyze polymerization, affording moderately high catalytic activity 1.93 × 10^5 g PE/(mol.Ti.h)]and high molecular weight polyethylene [5.63× 10^5 g/moll. The high temperature gel permeation chromatography (GPC) curve of polyethylene obtained revealed a single peak, but the molecular weight distribution (MWD = 3.21) is obviously broader than that of the similar mononuclear titanium complex. The melting points of the obtained polyethylene reaches 138 ℃, indicating that the polyethylene is of high crystallinity.
文摘-The i. r. spectra of Na4 [UO2 (CO3)3], Na [UO2 (OH)3] and the surface species of uranium on HTO underthe condition of flowing natural seawater and concentrated seawater (NaCl-NaHCO3-U) were recorded, with the bands of urany! of surface species obtained and the finding that iigands of surface species besides HTO are mainly water and OH, and there are some CO32- groups under the condition of natural seawater. Some relations between the complex properties and the j. r. spectroscopic characters for uranyl complexes were studied, and the transferred change quantity of surface complex was calculated.Structure models for surface species of adsorption are herein presented and the mechanism for uranium adsorption is deduced.
基金Project supported by the Science Foundation of Jiangsu Province (No. BK2005030)Acknowledgements Li Yahong thanks Aaron 0dom of Michigan State University for many helpful discussions and the authors appreciate the aid of Zhang Wenhua with the X-ray diffraction studies.
文摘Two ligand bridged binuclear titanium complexes Ti2(bppda)3(NMe2)2·3THF (1) and Ti2(bppda)3(NEt2)2·3THF (2) and one bis-ligand coordinated mononuclear complex Ti(bppda)2 (3) (ligand- HEbppda=N,N'-Bis(2-pyrrylmeth- ylidene)-1,2-phenylenediamine) were synthesized by adjusting the ratio of the starting materials and the reaction speed. The complexes were fully characterized with NMR, elemental analysis and X-ray crystal diffraction. The catalytic activity of the complex 1 to phenylacetylene hydroanilination reaction was also investigated.
基金financially supported by the National Natural Science Foundation of China(Nos.21272142 and U1362204)the Natural Science Foundation of Shanxi Province(No.2015011015)
文摘The trichlorozirconium η~2-hydrazonides(R=H, A; R=CH_3, B) were synthesized through the finely controlled stoichiometrical reactions of anhydrous zirconium tetrachloride with the lithium salt of either 1-(furan-2-ylmethylene)-2-phenylhydrazonide or 1-(furan-2-ylethylidene)-2-phenyl hydrazonide in the solvent tetrahydrofuran(THF), respectively. These complexes were highly sensitive to air and moisture due to solely using less bulky ligand of hydrazonides. The molecular structures of the title complexes, determined by means of single crystal X-ray diffraction, were found to be the distorted pentagonal bipyramid geometry around zirconium atom, with three chlorides and the hydrazonato ligand acting as the η~2-coordination mode as well as two incorporated THF molecules. Upon activation with either methylaluminoxane(MAO) or modified methylaluminoxane(MMAO), both complexes A and B exhibited catalytic activities toward ethylene polymerization, producing polyethylenes with ultra-high molecular weights.